DESCRIPTION: (Adapted from applicants' description) Atypical nevi are risk factors for melanoma and may precede as many as half of the melanoma tumors. The ability to self-diagnose atypical nevi has important implications for screening efforts aimed at prevention and early detection of melanoma. A recent mail survey in the Uppsala Health Region of Sweden obtained 50,000 questionnaire responses from women aged 35-55.Survey participants were asked to examine their lower extremities for irregular nevi resembling those shown in color photographs. The applicants propose to conduct a validation study to evaluate the ability of these study respondents to self-report atypical nevi. They will use a two-stage sampling procedure in which 2,000 questionnaire respondents are initially selected to determine the prevalence of self-reported atypical nevi. Of these, a sample of 400 respondents will participate in the validation study. The subsample will be stratified according to the presence or absence of self-reported atypical nevi. The accuracy of self-reported nevi will be evaluated by comparing the results of self-screening to the results of a physician-conducted skin examination. Information from the first and second stage samples will be combined to form efficient estimates of sensitivity, specificity, and the prevalence of atypical nevi. If it can be shown that atypical nevi are accurately self- reported, large population surveys aimed at targeting high risk groups for intervention might be inexpensively conducted through mail surveys. In addition to screening applications, the validation study may provide a foundation for population-based follow-up studies of melanoma risk, and case- control evaluations of risk factors for atypical nevi.